Why do so many scientists tend to be utterly dogmatic when new research challenges their fundamental assumptions?

Their close mindedness terrifies me because they are increasingly relied on in decision making -- like vaccines, for example. I thought science is centered around an admission of infinite ignorance? At any moment we can be made aware of new information that completely changes our understanding of the world because the truth is not hardwired into us. They are more and more looking like a clergy caste for the post-God state.